Hi
Magento is probably the most solid e-Commerce platform around. If you own an online store, you probably have given some consideration to using Magento on your site. Even big names like Nike, MotherCare, and Bazaar are on Magento.
Given below are some of the extensions that are important:
MatrixRate
Olark
XML map creator
Magento-Wordpress Integration
Yotpo

These i consider as benefits when using Magento:
Free. Its Community Edition has a lot of features and it's completely free.
Scalability. Magento was written in PHP, so you can easily add new features and scale your solution.
Thousands of extensions. If you want a feature, probably there is an extension to add it to your store.
A big, fast-growing and talented community of developers.